sar -b: is applicable to non O.S. buffered Filesystems???

[Juan Francisco Esteve_1]

Hi all,

I've got output from command "sar -b" data gathered in one system. This system has the most "active" FS (in terms of read/write) with mount option to bypass O.S. buffering.

The rest of FS's are configured to use O.S. buffering and these FS's are suppossed to have a low activity (or at least much lower than the others that are excluded from O.S. buffering).

In order to a suitable analyze of "sar -b" output....I've got a doubt:

how do I consider FS with no buffering option??

a) Should I suppose those FS are not included on sar -b output??

b) Should I suppose those FS are included on sar -b output (with 100% or 0% Hit ratio)??

NOTE: The behavior of my server is 100% most of the time for read cache hit ratio, and radmdom (0%-60%) for write cache hit ratio except when a high I/O activity takes in place, for this momment write cache hit ratio raises to be close 100%.

Thanks for any help to my questions.

Johnny

[Steven E. Protter]

1) Can we see the sar -b output, at least4 sample and summary.

argus:/users/sprotter/cluster# sar -b -i 10 20

HP-UX shmuelbagel B.11.00 U 9000/800 11/10/05

15:05:31 bread/s lread/s %rcache bwrit/s lwrit/s %wcache pread/s pwrit/s
15:05:51 0 24 100 0 1 9 0 0


I think you'll see no ouptput in the colums that have to do with buffering if the FS has no buffering.

All in all it really depends whats really goin on in the filesystem. Even if you have buffering turned off at the OS level, the application can buffer and skew results.

Perhaps collect some broder, parellel data:

http://www.hpux.ws/system.perf.sh

SEP

[Juan Francisco Esteve_1]

What exactly do you mean with:

"Even if you have buffering turned off at the OS level, the application can buffer and skew results"??

The FS that bypass O.S. bufer cache has the options...

ioerror=mwdisable,largefiles,mincache=direct,delaylog,convosync=direct

And I suposse they use HP Online JFS and Veritas.

May be that in spite of how is set the FS, there are some system routines that can use bufer cache??

Thanks in advance....

Juan